U.S. Pat. No. 3,795,361, was granted Mar. 5, 1974 in the name of C. Y. Lee to the assignee of the present invention. The background of that invention is applicable to the present invention, and it is therefore incorporated herein by reference.
It is advantageous to provide a baffle within the centrifuge bowl; which baffle, in use, extends through the inner layer of separated light phase material and into the outer layer of separated heavy phase material. Preferably, the outer edge or portion of such baffle defines with surrounding structure, e.g. the inner surface of the bowl, a restricted passageway for the underflow of heavy phase material from the separating zone on one side of the baffle to the discharging zone for heavy phase material on the other side of the baffle. With this arrangement, heavy phase material such as flowable solids may be discharged containing a controlled or reduced amount of light phase material. For example, solids may be discharged in dryer condition than was possible prior to the invention of the cited patent.
Means are provided to pressurize the heavy phase material and thereby promote its advance through the restricted passageway toward its discharge port in the tapered end of the bowl, such advance also being aided by the screw conveyor. The most convenient form of pressurizing means is the provision of light phase discharge ports having weir surfaces disposed closer to the rotational axis of the bowl than are the weir surfaces of the heavy phase discharge ports, thereby cooperating with the baffle to maintain a deep layer of liquid or other separated light phase material in the separating zone. The extra pressure head provided by a deep layer of light phase material provides the desired added pressure on the heavy phase layer. A centripetal pump may also be employed to control the rate of light phase discharge from the bowl and, thus, also control the level of the light phase layer remaining in the bowl.
The present invention is directed to accomplishing the same or a similar result as with the construction of the cited patent, but by means of a smaller and more simply constructed and installed baffle. It is an object of the present invention to provide an economical but effective baffle for the purpose described.